feat(sync): add delivery cost, discount tracking and import settings

Parse delivery.total and discounts[] from GoMag JSON into new
delivery_cost/discount_total fields. Add app_settings table for
configuring transport/discount CODMAT codes. When configured,
transport and discount are appended as extra articles in the
Oracle import JSON. Reorder Total column in dashboard/logs tables
and show transport/discount breakdown in order detail modals.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/database.py

@@ -104,7 +104,9 @@ CREATE TABLE IF NOT EXISTS orders (
     factura_total_tva     REAL,
     factura_total_cu_tva  REAL,
     invoice_checked_at    TEXT,
-    order_total           REAL
+    order_total           REAL,
+    delivery_cost         REAL,
+    discount_total        REAL
 );
 CREATE INDEX IF NOT EXISTS idx_orders_status ON orders(status);
 CREATE INDEX IF NOT EXISTS idx_orders_date ON orders(order_date);
@@ -140,6 +142,11 @@ CREATE TABLE IF NOT EXISTS web_products (
     order_count     INTEGER DEFAULT 0
 );
 
+CREATE TABLE IF NOT EXISTS app_settings (
+    key   TEXT PRIMARY KEY,
+    value TEXT
+);
+
 CREATE TABLE IF NOT EXISTS order_items (
     order_number   TEXT,
     sku            TEXT,
@@ -303,6 +310,8 @@ def init_sqlite():
             ("factura_total_cu_tva", "REAL"),
             ("invoice_checked_at", "TEXT"),
             ("order_total", "REAL"),
+            ("delivery_cost", "REAL"),
+            ("discount_total", "REAL"),
         ]:
             if col not in order_cols:
                 conn.execute(f"ALTER TABLE orders ADD COLUMN {col} {typedef}")